Stalling on an exercise occurs when you haven't been able to make any progress on that exercise for several workouts. The rule of thumb that I use is 3 consecutive workouts with no progress in weight or reps.
If you make progress with just a tiny bit of weight or a single rep, then you are definitely not stalling. Any progress you make is progress. It doesn't matter how small that progress may be. As long as you are making strength gains, you are doing great.
You have to pay attention to your performance during each weight lifting workout. It really helps to take notes about how you feel during each set, each workout, and each day in general.
For example, if you really struggled during a specific set to reach all 5 reps on your last set of an exercise… should you really increase the weight by the normal increment?
Were you just having a bad day in the gym?
Are you reaching your strength limits?
Did you eat well that day and sleep well the past few days?
Have you been working out for at least a few months and have been feeling drained lately?
Have you been using too much intensity or too much volume? Would a few extra days of rest help you out?
You have to know what's going on with your body in order to make the right choice for the next workout.
If you're reaching your strength limits, you should only increase by a small amount. If you didn't sleep well, try to get a nap in or get to bed earlier the next night. If you didn't eat well, you have to fix that immediately. You should always be eating nutrient packed foods only.
You'll learn after some experience how long you can go and how hard you can push your body before you begin to overtrain.
For example… when I first started using advanced beyond failure training, I could only last 5 weeks max before I started to overtrain. I made great progress during those 4 to 5 weeks, but I would hit a wall at the 4 to 5 week timeline every single time I tried.
If I could just get the programs to last longer without overtraining, I could make amazing progress instead of just great progress.
I scaled back the frequency of the workouts to give my body more time to recover between workouts. This worked great and I learned exactly what my body could take and how to prevent stalling (for me) with that style of training.
Everyone is different. Everyone tolerates different amounts of volume, frequency, and intensity. You have to learn your body. You have to learn how to anticipate when you are doing too much and make appropriate changes.
You have tons of options here. Inserting rest days is very easy to do. Improving sleep, diet, water intake is also easy to do. Make sure you try all the easy options first.
Then, if you need to scale back on volume, intensity, or frequency do so. Try decreasing one of those if you feel like you might be close to stalling. Inserting rest days decreasing frequency so you might give that a shot first.
Stalling is going to happen at some point because you just can't increase the weight forever. If you can prevent stalling for as long as possible, you will get much better results. You'll get better at anticipating stalling, and you'll learn how to make changes so you get better results.
This isn't difficult once you learn more about your body and how much it can take. It actually gets rather easy after just a bit of experience.